1. Field of the Invention
The invention relates to a magnetic field sensing apparatus and a magnetic field sensing module.
2. Description of Related Art
As portable electronic apparatuses become more and more popular, the technology of electronic compass capable of sensing the geomagnetic direction becomes highly valued. When the electronic compass is used in a small-sized portable electronic apparatus (e.g., smart phone), it is desired that the electronic compass permits tri-axial sensing in addition to meeting the requirement on size, because the user may hold the phone inclinedly when holding the phone with his/her hand, and the phone may be held at various different angles.
In the conventional technology, a composite sensing element is used to accomplish tri-axial sensing. Specifically, tri-axial sensing is accomplished by using two giant magnetoresistance (GMR) multilayer film structure (or tunneling magnetoresistance (TMR) multi-layer film structure) and a Hall element disposed perpendicular to each other. However, since the sensing sensitivity of the Hall element is different from the sensing sensitivity of the GMR (or TMR) multilayer film structure, the difference may make the precision on one of the axes different from the precision on the other two axes. Thus, when the user rotates the portable electronic apparatus to a different angle, the sensing sensitivity to the same magnetic field may become different, thus causing confusion.
In the conventional art, in order to accomplish multi-axial sensing of magnetic field, it is common to adopt two or more manufacturing processes. Namely, a multi-axial magnetic field sensing module requires two or more wafers to be manufactured. The manufacturing processes are thus complicated, so it is difficult to reduce the manufacturing cost. Moreover, such manufacturing processes also make it difficult to further reduce the size of the magnetic field sensing apparatus.